-LRB- CNN -RRB- -- Andrew Sable was n't in the market for new wheels , but he says the federal `` cash for clunkers '' program helped him get an offer he could n't refuse .

`` I 'd have been foolish not to take it , '' said Andrew Sable , who got $ 9,000 for his 1993 Jeep Grand Cherokee .

The gas-guzzling 1993 Jeep Grand Cherokee his college-student son drives went bad last weekend . Ordinarily Sable would have fixed it , even though the vehicle was worth perhaps $ 2,000 at best .

But , aware of the program that started this month , Sable took a $ 4,500 federal credit this week to trade in the Jeep and buy a new , more fuel-efficient Chrysler PT Cruiser . And Chrysler , eager to sell vehicles , threw in its own $ 4,500 incentive .

The $ 9,000 in savings knocked the price to $ 8,900 before taxes and fees .

`` I 'll never get $ 9,000 for this old vehicle -LSB- any other way -RSB- . I 'd have been foolish not to take it , '' the 43-year-old Sable , an insurance underwriter living in North Bellmore , New York , told CNN after filing a report with iReport.com . He 'll drive the PT Cruiser and let the son drive his Nissan . iReport.com : Read Sable 's account of the purchase

Under the $ 1 billion program , people will be given credits of $ 3,500 to $ 4,500 to replace gas guzzlers -- generally vehicles with a combined city/highway fuel economy of 18 miles per gallon or less -- with new vehicles that are more fuel efficient . The old vehicles are crushed or shredded . Watch CNN 's Gerri Willis explain the `` cash for clunkers '' program ''

The exact credit offered through the program -- officially called the Consumer Assistance to Recycle and Save Act of 2009 , or CARS -- depends on how many more miles per gallon the new vehicle gets .

Fuel economy thresholds for new vehicles vary according to type . New cars must have a combined city/highway fuel economy of at least 22 mpg . New SUVs and small or medium pickup trucks or vans must get at least 18 mpg . New large vans and pickups must get at least 15 mpg .

The government put Sable 's old Jeep at 15 mpg . His new PT Cruiser , which the program classifies as an SUV , gets a combined 21 mpg .

Part of the program 's intent is to get vehicles with low fuel efficiency off the road . Caroline Radtke , a 31-year-old who wrote about her purchase on iReport.com , was happy to oblige .

Radtke and her husband this month got a $ 4,500 CARS credit for trading in their 2000 Isuzu Trooper -LRB- 15 mpg -RRB- to buy a new Volkswagen Jetta SportWagen , a diesel-powered car that the program lists as getting 33 mpg . After the credit , they paid just under $ 26,000 .

`` What was going out of my -LSB- old -RSB- vehicle was bad for the planet , and you 're putting so much financially into the stupid thing to fill it up because it runs out so fast , '' Radtke , a freelance graphic designer living in San Antonio , Texas , told CNN after filing her iReport . `` After driving it for eight and a half years , I wanted something more productive financially and more friendly to the Earth . ''

The couple would have bought a new car without CARS , but the credit probably allowed them to get a nicer car than they otherwise would have , Radtke said . If they had sold the Trooper themselves , they might have gotten $ 3,000 if they were lucky , she said . iReport.com : Radtke 's purchase

The CARS program is n't for everyone . The credit wo n't go toward used-car purchases . Also , people looking to get rid of their under-18-mpg vehicle might find they can get about the same or more than a CARS credit by selling it .

But the program worked just fine for iReporter Julie Callahan , a Salt Lake City , Utah , woman who was looking to replace her 1990 Chevy C1500 pickup truck , which had more than 350,000 miles and is rated at 15 mpg .

She and her husband already had a newer vehicle , but she used the truck to go to work and for other in-town purposes . But lately it started having shifting problems , and it was occasionally slipping going uphill .

Like Sable , Callahan , 39 , got $ 4,500 this week to turn in the old vehicle and buy a new PT Cruiser . And , like Sable , she also received a separate $ 4,500 credit from Chrysler . She 'll be paying about $ 10,000 for her new vehicle after taxes and fees .

The $ 9,000 she saved with the credits from CARS and Chrysler is n't too shabby , considering she figures her old pickup was nearly worthless because it had so many miles . iReport.com : How Callahan got $ 9,000 for her truck

`` Without the incentives , I probably would n't have purchased a brand new vehicle , '' Callahan , who runs a science outreach program at the University of Utah , told CNN after filing her iReport .

Unless it is renewed , the program will end November 1 or when funds allotted by Congress run out , whichever happens first .

Trade-ins must be less than 25 years old , and their titles must be free of any liens . Consumers can go to a Web site , cars.gov , to learn the program 's rules . FuelEconomy.gov : See if your vehicle qualifies for CARS

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N.Y. man was n't looking for new vehicle , but credits , circumstances changed plans

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Program gives credits of $ 3,500 to $ 4,500 to people who trade in gas guzzlers

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Recipients must buy new vehicles that are more fuel efficient

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Texas woman glad program helped her buy more fuel-efficient vehicle